Conventional techniques for measuring packet transit times, i.e., latencies, through a network, e.g., ping and traceroute, rely on test packets. In these techniques, the test packets are actively inserted into the network, generating additional network traffic which may degrade the quality of service (QoS) over the network. Moreover, the test packets may not follow the same routes as existing network traffic, leading to inaccurate results.
Techniques relying on packet matching have been developed to overcome some of these problems. In these techniques, matching packets, i.e., the same packet at different network locations, are identified in the existing network traffic. A technique in which matching packets are identified at the edge of the network by comparing packet sequence numbers is disclosed in U.S. Pat. No. 8,243,599 to Becker et al., issued on Aug. 14, 2012, which is incorporated herein by reference, for example. However, a single sequence number does not provide enough information to uniquely identify each packet throughout the network. Techniques in which matching packets are identified at different locations in the network by comparing a packet identifier generated from header fields and part of the payload are disclosed in U.S. Pat. No. 6,873,600 to Duffield et al., issued on Mar. 29, 2005, and in U.S. Patent Application Publication No. 2006/0077902 to Kannan et al., published on Apr. 13, 2006, which are incorporated herein by reference, for example. However, in these techniques, the packet identifiers are generated in a computationally expensive manner from more and/or deeper information than necessary to uniquely identify each packet throughout the network.
Therefore, an improved method and system for identifying matching packets are desirable.